Research On Flight Control Law Of Transition Phase Between Hover/low Speed And Forward Flight For Unmanned Helicopter

Unmanned helicopter is a helicopter which is controlled by wireless remote or procedure, it is valuable in military and civilian because of its special flight characteristic. The flight phase can be distributed into four stages, such as take-off/landing, hover/low-speed, transition and forward flight,the transition phase is a stage between hover/low-speed and forward flight. In view of the specialty of the transition phase of sample unmanned helicopter, this article will design control law of each channel and raise a viable control program by analyzing and researching its mechanism of movement and object properties, it will solve some control problems of transition phase and improve the stability,accuracy and safety of the transition phase of flight control.We are hard to get an accurate non-linear model because of high order, strong coupling, instability of the unmanned helicopter, so in this paper, based on the linear model group, will analyze the object properties of the unmanned helicopter in the transition phase from the view of balancing feature,modal characteristics and channel coupling, as the basis of follow-up control law design and control program design.According to the flight characteristics of unmanned helicopter, transition phase can be divided into hover-to-forward flight transition and forward flight-to-hover transition. Hover-to-forward flight transition contains fixed-high acceleration mode and climbing mode, forward flight-to-hover transition contains fixed-high deceleration mode, sliding mode and fixed-high fixed-point recycling mode. According to the function and demand of each mode, coming up with the control scheme and strategy through designing the control law of each channel by using PID control method.At last, designing the air route which includes the whole flight process and each mode of transition phase and simulating under the equivalent simulation environment. By analyzing the flight simulation data under the disturbance of no-wind and wind, it verifies that the control law and control strategy of the transition phase have a good control effect and a certain robustness.